Ph Rising.

[ShoC]

I did have an older topic on this but can't find it to update it.

My current tank for some unknown reason the PH has risen to 8.4
out of the tap my PH is a lovely 7.1

I have no rocks added just plants and bogwood.

I sat my out of tap water (dechlorinated) for 1 week and tested the ph had risen to
7.6 so what the heck can be raising my PH so much??

my next task is to sit some of my gravel in a tub of water and test 1 week later to see if the gravel is the problem.
even tho its said to be inert.

this is is the site.

http/www.pettex.co.uk/gravel.html#

Jet Black gravel near the bottom.

I have no idea how to battle this all I can think is to maybe buffer my water before putting it in and slowly get it back down again..

sorry I cant provide GH/KH but 1 week stand should show its not to bad??

thanks for any help
Carl

Ps.
Tank is 3ft 122litres
with filters.

EHEIM 2236 and Tetratec EX1200 (never can have to much filtration

 

[dthoffsett]

I don't know if I have enough knowledge to help you, but I'll do what I can, and at least bump this up for others to read.

The way I understand it, a PH rise (in a tank with inert substrate and decor) can be caused by the minerals present in your water breaking down. In a closed system (ie. a fish tank), those minerals build up over time. Water changes help, but even though the minerals present in your tank break down over time to buffer the PH, when introducing fresh water, you are adding more minerals. I'm guessing your KH is pretty high, which is also why you are seeing a rise in the water you set out to test.

Post the KH and GH once you get those tests.

What do you have the tank stocked with? I see you said you just added bog wood and live plants, those "should" help lower your PH a little bit, adding CO2 to your tank will also help.

How fast is your PH rising in the tank, are there PH swings every day, or is it slowing rising over several days? Is the rising PH a new thing, or something that has been happening since you set up the tank?

Hope I explained things a little better, and hopefully someone with more knowledge will be able to add more, or correct any mistakes I've made.

 

[ShoC]

I had this happen in two Tanks I have (only got the one now)
the test water was enclosed in a bottle,

I couldn't say how fast it is rising sadly
but is for sure 8.4 at the end of the week even when I do a 50% water change.

 

[merry78]

You could try decreasing o2 input and/or lighting so that your plants are taking o2 in and releasing co2 for a greater amount of time each day.....watch your fish tho'.
Otherwise you might have to look at co2 injection.
Sorry but i have no idea why it might be continually rising, i had this in one tank and found it was from the gravel (even tho it was lfs gravel for freshwater), so i changed the gravel and have no probs now.
is R/O an option for you?

 

[ShoC]

R/O is an option but my g/f will kill me if I spend more money =)
My lighting is 2.4w per gallon or something similar.

I was meant to put some gravel in a jug of water and see what happens (thanks you reminded me)
dont know if I should use the tank gravel or the new bag of it that I have.

Mind you my 2nd tank had a different gravel and still worked

 

[rabbut]

It is possible that there is CO2 desolved in your tap water, as as it is gradualy driven off/used by plants, the pH rises. CO2 comes with carbonic acid, lowering the pH, as CO2 is driven off, the carbonic acid is broken down into a form of KH, buffering up the pH of the water, both by removing acids, and creating alkalines. Hope thats clear enough to be understood.
Rabbut

 

[ShoC]

Makes perfect sense..
either way it's driving me crazy.

 

[rdd1952]

Since the water you left sittin ot also showed an increase in pH, I would agree that your KH is high and that is the reason it is rising. Even at that though, I can't see it rising to 8.4 or even higher since that's what you got after a water change. I'm pretty much at a loss as to how itwould get that high without some outside agent in the tank causing it. Are you using any type chemicals other than dechlorinator?

You could try decreasing o2 input and/or lighting so that your plants are taking o2 in and releasing co2 for a greater amount of time each day.....watch your fish tho'.
Otherwise you might have to look at co2 injection.

Actually, plants take in CO2 and release O2. Decreasing lighting would have the effect of reducing O2 some as the plants would use less CO2 but I don't know that it would be enough to have a major effect.

 

[Musho3210]

i would think that the tap water has high CO2 level, as the water is getting agiated the CO2 leaves therefor raising the pH. But you must have a LOT of CO2 in the water to bring it that low...... what test kit are you using?

 

[ShoC]

I have an API master test kit.
I have a Co2 drop checker that I could test on standard tap water...
so minus the Co2 from the tap water ( assuming it is high in it ) the waters natural waters PH would be fairly high...